Pulsatile flow past multiple cylinders: A model study of blood flow in an artificial lung

Abstract

Pulsatile flow across two circular cylinders with different geometric arrangements is studied experimentally using particle image velocimetry method and numerically using the finite element method. This investigation is motivated by optimizing the design of a total artificial lung (TAL), a potential bridge to lung transplantation. Blood flow through the TAL is generated entirely by the right ventricle of the heart and no external pump is utilized, thus blood flow inside the TAL is pulsatile. The oxygen-poor blood flows across a bundle of hollow fibers that oxygen-rich air flows through. Understanding time-dependent flow around these fibers is crucial for optimizing design since convection is the dominant transport mechanism in the bulk blood flow. The vortex structures resulting from three different arrangements of cylinders (tandem, side-by-side, staggered) in pulsatile flow with Reynolds numbers of 1, 3, and 5 and Stokes numbers of 0.18 and 0.37 were investigated. Consistent results were observed in the numerical and experimental results. These results reveal that the vortex structure depends strongly on the geometric arrangement of the cylinders. The vortex strength is highly dependent on the Reynolds and Stokes numbers. These findings suggest design criteria for enhancing mixing and reducing pressure drop across the TAL. © 2008 Springer-Verlag.